Composing requirements for goal-oriented system behaviors using an extended form of use case

Abstract

Use Cases have been shown to be an e ective construct to express system requir ements in terms of environmentally visible behaviors. However, re nement of the Use Case into a set of corresp onding system r equir ements is only indirectly supporte d by Use Case semantics that fo cus on envir onmental objects and their interaction with the system. In this paper we use a scenariolike extension to the Actor-Oriented Use Case called a System-Oriented Use Case which extends the Use Case to a set of system behaviors. We enrich the SystemOriented Use Case with a F usion-like notation to encode the speci c ation of system b ehaviors constr aine d b y the Actor's r ole and in support of the Actor's go al.Our extensions produc eincr ementallyless abstr act requir ements that terminate in Life Cycle expr essions traceable to the Use Case and A ctor. We provide formal de nitions for role, go al and the r esponsibilities of liveness and safety.